CAUTION With the installation of
the equipment in Zone 0 Group II area it has to be ensured that sparks due to impact or
friction do not occur.
Wiring requirements
The cable glands and cables used for
wiring the device must not impair the Ex protection.
Unused lead-throughs must be sealed
using Ex compliant plugs.
Select a strain relief option that suits
the application (either use cable glands that include strain relief or install separate
clamps: see IEC 60079-14).
CAUTION Connect only de-energized
wires. Never switch on the power supply input before completing the wiring and closing the
transmitter body.
Intrinsic safety
The overvoltage category of HMT370EX
transmitters is I (non-mains equipment), and ambient pollution degree
is 4, as specified in IEC 60664-1. For intrinsically safe input parameters, see Table 1.
Table 1. Intrinsically safe input
parameters
Parameter
Value
Associated apparatus entity parameters
Ui
28 VDC
Uo ≤ Ui
Ii
100 mA
Io ≤ Ii
Pi
700 mW
Po ≤ Pi
Ci
12.1 nF
Co ≥ Ci + Ccable
Li
16 µH
Lo ≥ Li+ Lcable
Using analog output test points
There are test points for measuring the
voltages and currents of the analog outputs, located above each screw terminal block as
shown in Figure 1. Accessing the test points on the component board requires opening the
transmitter enclosure. Figure 1. Location of test points and service
port
1
Multimeter test points for analog output channels 1 and 2
2
Service port for PC connection
CAUTION
The transmitter body enclosure must not
be opened in an explosion hazardous area, unless a safe work permit has been issued in
accordance with the standard IEC 60079-14. Either remove the transmitter from the
hazardous area before opening the enclosure, or ensure that an IEC 60079-14 compliant
safe work procedure has been implemented in the hazardous area.
Use an intrinsically safe multimeter that will not cause the intrinsically safe input
parameters listed in Table 1 to be exceeded when it is connected in series (current measurement) or
parallel (voltage measurement) to the associated apparatus.
Using the service port
The service port (see Figure 1) must
only be used in a safe area. Either remove the transmitter from the hazardous area or ensure
that a safe work procedure has been implemented in the hazardous area. Only use the Vaisala
accessory PC connection cable with the service port.
Maintenance
The probe (includes probe body and head) can
be detached and replaced by the user. The probe head filter (see Figure 1) is also user-replaceable. For other maintenance requirements, contact
Vaisala.
CAUTION The probe can be detached
and changed when HMT370EX is powered. Any other live maintenance, including changing the
probe head filter, is not allowed.
CAUTION To maintain the required
Ex protection, inspect the equipment for signs of deterioration at an interval of 6 months.
If maintenance requirements are found, contact Vaisala.
Installation restrictions
CAUTION To maintain the required
Ex protection, do not install the transmitter model with an LCD display in a location where
it is exposed to direct sunlight.
